build: rename binary from node to iojs

* rename the build targets

* update the test runner to use `out/{Debug,Release}/iojs`

* update the installer to install the iojs binary

* update one test that explicitly checks for the binary name

PR-URL: https://github.com/iojs/io.js/pull/262


Reviewed-By: Bert Belder <bertbelder@gmail.com>